Giving a square for the knight on f3, but now Black wins a pawn.
30... g8g7  31. e4d2 After this move Black gains a clear advantage. Nakamura probably realized by now that he had no advantage and that it would be nearly impossible to play for a win. It was better to advance the kingside with 31.h4 or g4 or to simply play something like 31.Kg2. 31... d5c3  32. d1e1  32... b6b5 Despite the material advantage, White's pieces can barely move.